1. Field of the Invention
The present invention relates to isolated polypeptides having xcex1-amylase activity and isolated nucleic acid sequences encoding the polypeptides. Further, the invention relates to variants of the xcex1-amylases of the invention. The invention also relates to nucleic acid constructs, vectors, and host cells comprising the nucleic acid sequences as well as methods for producing and using the polypeptides. Further, the invention also relates to compositions for laundry, dish wash and/or hard surface cleaning.
2. Description of the Related Art
For a number of years xcex1-amylase enzymes have been used for a variety of different purposes, the most important of which are starch liquefaction, textile desizing, starch modification in the paper and pulp industry, and for brewing and baking. A further use of xcex1-amylases, which is becoming increasingly important, is the removal of starchy stains during washing with a detergent at alkaline pH.
Examples of commercial xcex1-amylase products are Termamyl(copyright), Duramyl(trademark), Natalase(copyright), BAN(copyright) and Fungamyl(copyright), all available from Novo Nordisk A/S, Denmark. These and similar products from other commercial sources have an acidic to a neutral pH optimum, typically in the range of from pH 5 to pH 7.5, and they do not display optimal activity in detergent solutions at alkaline pH.
WO 95/26397 discloses an xcex1-amylase from a Bacillus strain.
WO 96/23873 describes variants of Bacillus amylases with improved performance under washing conditions.
U.S. Pat. No. 5,147,796 describe an alkaline pullulanase having alpha-amylase activity. FIG. 2b of the document shows optimum amylase activity at pH 8-8.5.
M. Takagi et al., J. Ferment. Bioeng., vol 81, No. 6, 557-559 (1996) describe an alkaliphilic alpha-amylase-pullulanase from Bacillus sp. The enzyme has optimum amylase activity at pH 9, but the activity drops rapidly at higher pH, and the activity at pH 10 is lower than at pH 7.
WO 97/00324 (KAO) discloses a gene encoding an alkaline liquefying xcex1-amylase derived from Bacillus sp. strain KSM-AP1378 with the deposited no. FERM BP-3048 suitable for detergents.
It is an object of the present invention to provide novel xcex1-amylases with improved performance in alkaline solutions, especially in alkaline detergent solutions at pH around 9-11.
The present invention relates to isolated polypeptides having xcex1-amylase activity and one or more characteristics or properties selected from the group consisting of:
(a) a polypeptide having an amino acid sequence which has at least 85% identity with amino acids for mature polypeptide amino acids 1 to 485 of SEQ ID NO: 2 or SEQ ID NO: 4;
(b) a polypeptide encoded by a nucleic acid sequence which hybridizes under medium stringency conditions with (i) the nucleic acid sequence of SEQ ID NO: 1 or SEQ ID NO: 3, (ii) the cDNA sequence of SEQ ID NO: 1 or SEQ ID NO: 3, (iii) a subsequence of (i) or (ii) of at least 100 nucleotides, or (iv) a complementary strand of (i), (ii), or (iii);
(c) an allelic variant of (a) or (b);
(d) a fragment of (a), (b) or (c) that has xcex1-amylase activity;
(e) a polypeptide having improved wash performance in alkaline detergent solutions, especially in alkaline detergent solutions at a pH around 9-11, and more preferably, at a pH around 9-10.5;
(f) a polypeptide having a temperature optimum determined using the Phadebas method (pH 9.0) in the range between 55 to 65xc2x0 C.; and
(g) a polypeptide having a pI between 7-8 determined by isoelectric focusing (Pharmacia, Ampholine, pH 35-9.3).
It is to be understood that the alpha-amylase of the invention may have one or more of the above characteristics.
Further the invention relates to variants of the xcex1-amylase of the invention. The present invention also relates to isolated nucleic acid sequences encoding the polypeptides and to nucleic acid constructs, vectors, and host cells comprising the nucleic acid sequences as well as methods for producing and using the polypeptides.